Tension and let-off device and method



Sept. 25. 1956 F. w. BREY 2,764,367

TENSION AND LET-OFF DEVICE AND METHOD Filed Sept. 27, 1955 2 Sheets-Sheet '1 ZZZ-7:5

FQANK W BQEY INVENTOR ATTORNEYS.

Sept. 25. 1956 F. w. BREY 2,764,367

TENSION AND LET-OFF DEVICE AND METHOD Filed Sept. 27, 1955 2 Sheets-Sheet 2 MOTION INVENTOR: FRANK W. BREY.

ATTORNEYS.

United States Patent TENSION AND LET-OFF DEVICE AND hfllTHOD Frank W. Brey, Spray, N. C., assignor to Fieldcrest Mills, Incorporated, Spray, N. C., a corporation of Delaware Application September 27, 1955, Serial No. 536,961

8 Claims. (Cl. 242-155) This invention relates to tension and let-off devices and more particularly to an improved device of this kind for a creel fed loom. It is an important object of this invenrality of single devices which perform the combined functions of tensioning and slack removing for individual yarns, all of whose tension and slack removing characteristics can be adjusted simultaneously from a single remote point both during creeling and while the yarn is at a stand still.

It is another object of this invention to provide a tensioning device whose tensioning effect is substantially independent of the diameter of the yarn remaining on the spool from which the yarn is withdrawn.

It is another object of this invention to provide an improved wheel type slack removing device wherein the device has unlimited travelwhen removing slack.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawings, in which:

Figure 1 is a somewhat schematic view of yarn handling equipment as embodied in a loom and a magazine creel equipped with a plurality of the improved yarn tension and let-off devices;

Figure 2 is an enlarged fragmentary view looking substantially along the line 2-2 in Figure l and showing an end view of one of the improved yarn tension and let-01f devices;

Figure 3 is an enlarged plan view taken along line 3-3 in Figure 2;

Figure 4 is a fragmentary side elevation looking at the right-hand side of Figure 2;

Figure 5 is an enlarged sectional view through a preferred embodiment of the tension Wheel taken substantially along line 5-5 in Figure 4;

Figure 6 is a schematic diagram showing a preferred electrical circuit for a plurality of the improved tension and let-01f devices.

The improved yarn tension and let-off device is particularly adapted to be used for maintaining tension in and removing slack from individual yarns in the course of the yarns movements to an apparatus or apparatuses having an intermittent'demand for either the same or varying amounts of yarn and wherein the yarn may be let back and sl'ackened by the apparatus or apparatuses at varying intervals. Such apparatus is embodied in various types of looms used in the manufacture of pile fabrics, such as carpets. These types of looms usually have some form of dipping device, such' as a needle or doup device,

which introduces warp yarn as pile in the fabric being woven.

In the manufacture of pile fabrics of the character described, it is common practice to feed pile yarns from individual yarn packages, spools, cones, bobbins or the like, mounted on racks or creels. In addition to the type of looms having a dipping device which introduces the yarn as pile in the fabric being woven, other looms use heddle arrangements to pull pile yarn over and under pile wires inserted in the weft direction during weaving. Still other looms use longitudinal pile wires and insert pile yarn directly over the pile wires or by interlacing the pile yarn with weft shots supported by the pile wires.

Various looms have been modified to use longitudinal pile wires, such as the Wilton, Axminster, Velvet and tufted needle types of looms. An example of one type of loom which has been so modified, is disclosed in U. S. Patent No. 2,437,378. In all such looms, it is necessary to maintain each of the strands of yarn at a predetermined uniform tension as well as to remove any slack that occurs in the yarn so that the dipping or other de vices always pull against taut yarn. Where an even pile fabric is being made, it is sometimes practical to use beaming rather than creeling, however, creeling is often used in order to avoid beaming.

Many types of tension and let-01f devices have been made heretofore to control the tension in and remove slack from individual yarns. Such attempts have involved the use of dancer rolls or the use of small compensating weights riding on each yarn strand to remove slack and separate weighted iron bar devices riding against the spools to maintain tension, this latter system being disclosed in U. S. Patent No. 2,142,025. Such attempts as these have been unsatisfactory because it has been necessary for the loomoperator to continually adjust individual weights, continually wind up individual spools or stop the loom to adjust tension and slack in the individual strands of yarns.

In such of these tension or drag devices as have operated on the principle of a Weight riding against the spool or against the yarn strand as it leaves the spool,

there has been a lack of uniform tension or drag due to the changing diameter of the yarn remaining on the spool. The fact that one device has been required for maintaining tension and a separate device for removing slack has also been an operating disadvantage. Various wheel-type electrical or magnetic drag devices are available which will produce a drag on a strand during high speed running of the strand over the wheel. These electrical devices however have the disadvantages of having to depend on high speed operation and of exerting no force on the yarn at standstill. These electrical devices therefore have no capacity for removing slack.

In order to overcome the difficulties heretofore encountered in maintaining uniform tension and removing slack in each of a plurality of yarns, I have provided a combined tension and slack removing device in the path of each of the yarns between the spool or other source and the apparatus which draws the yarn, each device comprising a slow speed electrical synchronous motor, of a type such 'as is employed for operating an electric clock, to the output shaft of which a pulley or wheel is secured. In its course from its source to the apparatus which draws the yarn, the yarn passes through an eyelet and around the corresponding pulley and through a second eyelet from whence it passes to the drawing apparatus. Passing the yarn completely around the corresponding pulley gives the pulley a good grip on the yarn, however, I have found it possible to operate the device simply by passing the yarn through the first eyelet over the pulley and through the second eyelet without passing ,the yarn completely around the pulley.

A voltage is continuously applied to the motors from a remote point by means of a suitable voltage Varying device such as an adjustableauto-transformer or rheostat interposed in a common electrical circuit to the motors. The amount of voltage applied determines the amount of torque present in each of the corresponding pulleys or Wheels and each of the motors is so arranged that while normally stalled, it tends to rotate the corresponding pulley or wheel in the opposite direction from that in which the yarn is drawn.

Accordingly, as the yarn is pulled or drawn toward the drawing apparatus or loom, it rotates the corresponding pulley in the opposite direction from which it normally tends to rotate, or in other words, it overcomes the torque of the motor and the amount of torque in the motor determines the amount of tension in the yarn. On the other hand, if the yarn tends to slacken, the pulley will reverse the direction of movement of the yarn to automatically take up the slack therein until the amount of tension in the yarn again corresponds to the amount of torque on the motor.

Referring to Figure l of the drawings, the invention is shown in association with a magazine creel broadly designated at and a loom broadly designated at 11,

the loom 11 being substantially of the type disclosed in said U. S. Patent No. 2,437,378. However, it is to be understood that the present invention may be used in association with any type of take-up apparatus which may demand a plurality of yarns intermittently or constantly and which may draw the yarns from a common source or a plurality of individual sources.

The loom 11 is of a type in which ground warp yarns 12 are drawn from a source, such as a pair of warp beams 13, and are formed into a base fabric by conventional weaving instrumentalities including an oscillatable reed 14. A row of dipping yarn guides such as needles or tubes 15 direct individual pile yarns P over longitudinal pile wires, not shown. The pile yarn guides 15 pass the pile yarns through the warp so weft shots are thrown thereover with each beat up stroke of the lay or reed 14. The improved yarn tension and let-off device is shown in association with a loom of this character merely to enhance the advantages of this device. Since the yarn guiding devices 15 have a dipping action, they direct pile yarns P to the pile forming zone with each downward stroke thereof and, as they subsequently move upwardly, they slacken the pile yarns P, or at least, tend to slacken the pile yarns P.

In this instance, each of the pile yarns P is shown as being withdrawn from an individual yarn source, such as a spool rotatably mountedon a shaft 21 fixed to the frame of the magazine creel 10. In their course to to the pile yarn guides 15, the pile yarns P pass from the spools 20 and engage the individual wheels of the tension and let-off devices, each of which is broadly designated at 23 and thence, all of the pile yarns P pass over a suitable guide roll 24 and then downwardly to the pile yarn guides 15. A cornber board, not shown, may .be inserted between guide roll 24, and the tension devices 23.

Each of the improved yarn tension and slack removing units comprises an electric slow speed synchronous motor having a gear reduction unit 31 thereon. The motor 30 may be of a type disclosed in a patent to vHansen et al., No. 2,298,373 dated October 13, 1942,

and the gear reduction unit 31 may be of a type such asis, disclosed in another patent to Hansen et al., No. 2,237,958 dated April 8, 1941.

There are other types of combination electric motors and gear reduction units which may be used for this purpose and, accordingly, a detailed description will not be given of the construction of the motor 30 and its gear reduction unit 31. However, the required characteristics of the motor are important. The motor must be self starting and, of a type which may be stalled eontinuously without injury to the motor. it also must be of a type in which the torque present in the output shaft thereof is proportional to the voltage applied to the motor and it must be capable of rotating its output shaft an unlimited number of revolutions in the direction opposite from the direction in which it is rotated when the torque therein is overcome by the pull on the pile yarn P. A hysteresis timing type motor is ideally suited to this purpose.

The gear reduction unit 31 of the electric motor 30 is suitably secured to a bracket or plate 35 which is preferably adjustably supported on the frame of the magazine creel 10 and, in this instance, the lower portion of the plate or bracket 35 has a boss 36 thereon which is penetrated by a rod or bar 37 suitably secured to and extending outwardly from the frame of the magazine creel 10 below the level of the spool 20. The output shaft of the gear reduction unit 31 is indicated at 40 and loosely extends through the bracket or plate 35 and has a suitable tension wheel or roller 41 fixed thereon.

The tension wheel 41 is preferably in the form of a V- pulley having irregular contiguous peripheral surfaces thereon. It is apparent that various other types of pulleys or tension wheels may be used, however, it is preferable that the periphery of the pulley has a relatively high coefficient of friction in order to prevent slippage of the corresponding yarn while on the pulley and that it be designed to allow the yarn to freely enter and leave the pulley. It is also apparent that where a particular group of yarns are subject to the same slackening effect, the number of tension devices required could be reduced by mounting more than one tension wheel 41 on an output shaft 40 by which each motor 30 would control more than one pile yarn P.

In order to assist in maintaining each strand of pile yarn P in engagement with the corresponding pulley or wheel 41, it is preferable that each yarn passes from the corresponding yarn source or spool 20 through a first thread guide or yarn eyelet 45 disposed closely adjacent the corresponding tension wheel 41 and then the yarn passes at least once around the pulley or over a sufiicient portion thereof to enable the pulley to grip the yarn and then through a second yarn guide or eyelet 46 and, thence, to the take-up means or, as shown in this instance, over the guide roll 24. The yarn guides or eyelets 45, 46 preferably straddle the tension wheel 41 in substantially tangential relationship to the periphery of the tension wheel 41. The yarn guides or eyelets 45, 46 may be supported in any desired manner and, in this instance, they are shown as being formed integral with the legs of a substantially U-shaped rod 47, suitably secured, as by welding, to the outer surface of the corresponding plate or bracket 45.

Referring to Figure 6, there is shown a preferred embodiment of an electrical circuit for controlling all of the tension devices or units 23 from a single control point. The amount of voltage applied to each of the electric motors 30, and, accordingly, the amount of torque applied to the output shaft of each motor 30, is controlled by a common voltage control means shown in the form of a variable autotransformer generally designated at 50 in Figure 6. The auto-transformer 50 is of the usual type having a winding 51 which is engaged by a brush or movable contact element 52. Assuming that all of the motors 30 are each of the 110 volt, 60 cycle, 4 watt type, opposite ends of the winding 51 of the auto-transformer 50 are connected to lead wires or conductors 53, 54 which extend to a suitable connector or plug 55 adapted to be connected to a suitable source of cycle, volt current.

By way of example, the voltage control unit or variable auto-transformer 50 may be of a type having a primary voltage of 115 volts, a frequency of 50 to 60 cycles, and an output voltage of from 0 to volts with a maximum kva. of 1 and a rated current of 7 /2 amperes.

I One end of the winding 51 of the auto-transformer also has a wire or conductor connected thereto and a wire or conductor 61 is connected at one end thereof to the movable contact element or brush 52. Most looms are equipped with an automatic stop motion such as that controlled by the usual drop-wires and, accordingly, the end of the wire 60 remote from the winding 51 of the auto-transformer 50 is connected to one side of a normally closed magnetic or solenoid switch 61 whose coil has wires or conductors 62, 63 connected to opposite sides thereof which extend to the normally open circuit of a stop motion indicated diagrammatically at 64 in Figure 6. The other side of the stop motion 64 has wires or conductors 65, 66 leading therefrom to respective lead wires 53, 54. Thus, upon actuation or energization of the electrical stop motion 64, it is apparent that the magnetic or solenoid operated relay switch 61 is opened.

The other side of the relay switch 60 has a wire 67 leading therefrom. Connected to opposite sides of each electric motor 30 are corresponding ends of wires or conductors 70, 71. All of the wires 70 are connected to the wire 61a and all of the wires 71 are connected to the wire 67. Although only three of the improved tension devices 23 are shown in Figures 1 and 6, it is apparent that any desired number of these devices may be arranged in parallel with the variable auto-transformer 50.

It is apparent that all of the improved yarn tension and let-off devices 23 are easily and quickly adjusted by means of the single auto-transformer 50 and, by simply adiusting the movable contact element 52 of the autotransformer 50 relative to the winding 51, it is apparent that the voltage applied to all of the motors 30 may be raised or lowered simultaneously to correspondingly increase or decrease the tensioning and slack removing characteristics of all of the improved devices. This obviates the necessity for the operator to perform the laborinus task of adjusting individual weights or of turning back individual spools or making any other individual adjustments as may be necessary in order to adjust the tension or remove the slack from any one or more of the yarns P.

It is thus seen that I have provided an improved yarn tensioning and let-off device for individually and continuously controlling the tension in each of a plurality of yarns from a common point of control and wherein the amount of tension in all of the yarns may be simultaneously varied from zero tension to maximum tension in accordance with the maximum amount of torque which may be developed in the shaft of each motor 30. It should also be noted that actuation of the electrical stop motion 64 of the loom, due to breakage of a warp yarn or for any other reason, will automatically break the circuit to all of the motors 30 thereby preventing, for example, a broken pile yarn from being entirely withdrawn from the loom by the corresponding yarn tension and let-ofi device 23. Though not shown, the stop motion 64 of the loom would, as it well known in the art, normally also be wired to stop the loom 11 proper. However, my tension and let-oft devices are otherwise electrically independent of the loom 11 drive and during a normal stoppage the devices have an inherent tendency to maintain a uniform tautness in the yarns.

Although each of the improved tension and let-off devices is shown as being disposed relatively close to the corresponding spool from which the yarn is being drawn, it is apparent that the improved devices may be positioned atany point along the path of the yarn. It should also be noted that by driving the tension Wheel 41 rather than the spool from which the yarn is withdrawn, the yarn always pulls against a torque operating at a fixed distance from the axis of the corresponding tension wheel, while on the other hand, if the yarn were withdrawn directly from the spool, it is apparent that the diameter of the yarn decreases as it is withdrawn from the spool. However, it is contemplated that a spool of yarn may be mounted directly on the shaft 40 of each of the motors 30 without departing from the spirit of the invention.

Although the present invention has been shown and described as a tension and let-ofi device in association with a loom, that is, wherein there is a relatively slow intermittent pull off of small lengths of yarn-like strands from individual sources and wherein there is a simultaneous need to maintain a substantially uniform tension and to remove any slack during the period when the yarn is not being pulled off, it is also contemplated that a plurality of the improved yarn tension and let-off devices, controlled from a common voltage control device or voltage regulating apparatus, may be used for controlling the tension in and removing slack from a plurality of yarns or other threads moving at relatively high speeds, such as in beaming or creeling, wherein tension must be uniformly maintained while in operation and where slack must be removed in the yarns each time the take-up means, beam or the creel, as the case may be, is stopped.

Heretofore, it has often happened that all or a substantial number of the yarns or threads would snap or break upon a creeling machine being started because of slack occurring in the yarns or threads by an overrunning of the usual types of tension devices at the time the creeling is stopped. However, the improved tension and let-01f devices will automatically remove any slack which would tend to occur at the time creeling is stopped. It is thus seen that each of the improved yarn tension and let-off devices has means for constantly producing a torque which acts as a dynamic drag on the yarn or thread and which pulls back the corresponding yarn or thread at any time that the pull on the yarn or thread becomes less than the drag torque.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

1. As a tension and let-off device for a creel fed loom having yarn take-up means, in combination, a plurality of stalled, self-starting, electric motors being constantly energized by a common voltage source, said motors each driving a wheel, a portion of the peripheral surface of which engages a yarn strand in its path to the loom and which constantly tends to pull said strand away from the take-up means, the pull of said wheel yielding to the pull of said take-up means.

2. The combination set forth in claim 1 above in which the voltage source is adjustable.

3. The combination set forth in claim 1 above in which the voltage source is electrically independent of the takeup means of the loom.

4. The combination set forth in claim 1 above in which the voltage source is adjustable and electrically independent of the take-up means of the loom.

5. The method of removing slack and providing let-off means for yarn strands being fed from a creel to the take-up means of a loom, comprising the placing of a driven, rotating member in the path of and engaging each strand so as to constantly pull said strand in a direction from said take-up means and allowing said rotating member to yield to the pull of said take-up means.

6. Apparatus for handling yarn wherein individual strands of yarn are drawn into a machine comprising a combined tension and slack removing device including a self-starting electric motor, a wheel frictionally engaging the corresponding strand in its path and being continuously driven by said motor with the direction of drive being against the direction of movement of the yarn to the machine.

7. A combined tensioning and slack removing device as set forth in claim 6 having electrical means for varying the torque of the motor.

8. That method of controlling the tension and preventing slack in a strand of thread being withdrawn by a machine from a source which comprises drawing the thread past and in engagement with a wheel located in the thread path between the source and the machine, constantly driving said wheel in a direction which tends to move said thread toward said source and allowing the force of said wheel on said thread to be overcome by the pull of said machine during drawing in of said thread.

References Cited in the file of this patent UNITED STATES PATENTS Cumming May 1, 1888 Duryee Sept. 14, 1954 Roughsedge Apr. 5, 1955 

